This disclosure relates generally to the field of hydrocarbon operations. In particular, the disclosure relates to operations for managing oil releases, which utilize mineral fines for subsea dispersant injection.
This section is intended to introduce various aspects of the art, which may be associated with one or more embodiments of the present disclosure. This discussion is believed to assist in providing a framework to facilitate a better understanding of particular aspects of the present disclosure. Accordingly, it should be understood that this section should be read in this light, and not necessarily as admissions of prior art.
In the oil and gas industry, hydrocarbons are accessed via a wellbore to provide a fluid flow path to a processing facility. Some of these hydrocarbon resources are located under bodies of water, such as lakes, seas, bays, rivers and/or oceans, while others are located at onshore locations. To transfer hydrocarbons from such locations, a pipeline and/or one or more different vessels (e.g., ship or tanker trucks) may be utilized through various segments from the wellbore and the processing facility.
Offshore leaks and/or spills may be problematic due to the hydrocarbons being released into a body of water. Typically, the hydrocarbons may form a slick on the surface of the water, which may be referred to as an oil slick. These oil slicks may form from hydrocarbons being released from subsea equipment or associated tubular members providing flow paths for hydrocarbons from subsurface formations.
Accordingly, various response techniques may be utilized to manage the hydrocarbon release and any associated oil slicks. One technique to manage the hydrocarbons released within a body of water is chemical dispersants. As an example, subsea chemical dispersant injection may be utilized for a subsea well blowout to reduce the amount of oil reaching the surface and ultimately stranding on shorelines. The use of subsea chemical dispersants may involve forming and maintaining stockpiles of chemical dispersant located near a well site (e.g., usually in vessels on the surface of the body of water), a pump and a conduit to transfer the chemical dispersant to a discharge point near any hydrocarbon release location, and a nozzle system or other system to inject the dispersant into the flowing hydrocarbons. If a well-control event occurs and hydrocarbons are escaping to the sea near the seabed, injecting chemical dispersants using this system into the flowing hydrocarbons escaping from the well causes the hydrocarbons to break up into very small oil droplets. These oil droplets have very slow rise velocities and may potentially stay in the water column indefinitely until most of the oil in the individual droplets is biodegraded by petroleum degrading bacteria.
Industry has developed contingency plans to use subsea chemical dispersant injection for drilling operations. These plans require establishing large chemical dispersant stockpiles of commercially available dispersants to meet requirements for worst case discharge flows. Further, although these chemical dispersant stockpiles are large, a worst-case discharge flow rate may exhaust the chemical dispersant stockpile in days to weeks. Once exhausted, any chemical dispersant resupply may involve re-allocating from other chemical dispersant stockpiles or by manufacturing additional chemical dispersants. Although industry has developed robust systems to ensure continued supply of dispersants during an emergency, stockpile transfer and manufacture are logistical challenges.
Suspended particulate matter (SPM) may be utilized to remobilize and disperse stranded hydrocarbons. As an example, U.S. Pat. No. 5,490,940 describes adding to the surface a mixture of fine hydrophilic mineral solids dispersed in an aqueous liquid that interacts with the oil to form buoyant mineral fines-oil floccules. These floccules reduce the tendency of the oil to adhere to solid surfaces or to re-coalesce, thus facilitating dispersion and removal of the oil.
The suspended particulate matter (SPM) techniques have also been utilized and further developed by the Department of Fisheries and Oceans (DFO) Canada. The DFO Canada and the Canadian Coast Guard conducted a field test in the St. Lawrence River to study the use of mineral fines to disperse oil slicks in concentrated ice. See, e.g., Lee, K., Z. Li, B. Robinson, P. E. Kepkay, X. Ma, S. Cobanli, T. King, M. Blouin, and B. Doyon. 2009. In-situ Remediation of Oil Spills in Ice-Infested Waters: Oil Dispersion by Enhancing Formation of Oil-Mineral Aggregates. In Proceedings of the 2009 Interspill Conference, 12-14 May 2009, Marseille, France. During this test, calcite-based fines were sprayed on surface oil slicks in ice and then the oil slicks were subjected to the prop wash of an icebreaker used to conduct the test. The icebreaker prop wash rapidly converted the surface oil slicks into oil plumes that transferred into the water column. The mineral treated oil formed stable dispersions and showed no evidence of resurfacing, while the untreated oil (i.e. subjected to same mixing but with no mineral fines applied) did not disperse effectively.
As the management of hydrocarbon leaks and oil spills is a time consuming operation, a need exists to enhance operations to manage hydrocarbon releases with enhanced methods and systems. In particular, a need exists for a new technique that is an alternative or supplement to the use of chemical dispersants in subsea dispersant injection. Injection of mineral fines is an alternative technique that may be utilized.